The objectives of the research are to establish the output of the two IgA subclasses in human urogenital secretions, and to correlate their ratio with recurrent infection by Neisseria gonorrhoeae. Subclasses will be measured by radioimmunoassay in normals and infected patients, including measurements in the convalescent period. We want to test the hypothesis that the predominant subclass of IgA in a given individual determines his or her susceptibility to gonococcal infection. The influence of IgA fragments generated by gonococcal IgA protease on leukocyte function will be determined. Chemotaxis will be examined in vitro using Boyden chambers and IgA attachment to leukocyte cell surface assessed by binding of isotopically labelled protein. Leukocyte studies are designed to examine the role of IgA protease in pathogenesis of gonorrhea. We will attempt to establish a new model for N. gonorrhoeae attachment to mucosal cells by using human rectal tissue maintained in organ culture as the host tissue, and will determine if urethral secretory antibody inhibits microbial binding to intestinal epithelium. In general, the research proposed is an effort to understand better the close relationship established between N. gonorrhoeae and epithelial surfaces bearing a well-developed secretory immune apparatus.